Effect of coma on the focusing of an apertured singular beam

Effect of coma on the intensity distribution and encircled energy of a singular beam, at the focal plane of a lens, is evaluated numerically by using Fresnel–Kirchhoff diffraction integral for two different values of topological charge. Results show lateral shift and flattening of the dark core. It is noticed that the singular beam with double topological charge is affected more by comatic aberration in comparison to the beam with single topological charge. We also verified our results by using optical transfer function approach.